Door sweeps and thresholds provide a weather tight seal at the base of exterior doors. With the arrival of the energy crisis of the 1970's, improvements have been made to door thresholds to make them more energy efficient. One of the biggest difficulty in maintaining a tight weather seal at an entrance door is the wear placed on the weatherstripping (door sweep) placed along the bottom of the door. As this material is compressed over time, gaps can form between the sill and the sweep or the stripping can tear, which allows cold air to pass under the door. To overcome this problem, several designs have been developed. Some representative designs are found in U.S. Pat. Nos. 3,475,866, 3,762,100, 4,003,162, 4,104,830, 4,287,684, 4,352,258, 4,387,535, and 4,565,033. All of these patents adjust the height of the sill in some manner to correct for the compression of the door sweep. These devices also allow a builder to adjust the height of the sill quickly when the door is being installed. Over time, as the door sweep loses its tight seal, the homeowner can readjust the sill as needed. Eventually, the door sweep no longer provides an adequate seal regardless of the adjustments made to the sill. When that occurs, the door sweep must be replaced and the sill re-adjusted. Although these maintenance procedures are not difficult, they are often overlooked or put off because they can be tedious. If ignored, however, the gap in the threshold seal can waste considerable amounts of energy in northern climates.